Preheat your oven to 375°F (190°C). Line a mini muffin tin with paper liners or grease it lightly.
In a mixing bowl, whisk together the flour, baking powder, baking soda, and salt.
In another bowl, whisk together the melted butter and sugar until well combined. Add the eggs and vanilla extract, and mix well.
Gradually add the dry ingredients to the wet ingredients, alternating with the milk. Mix until just combined. Do not overmix.
Fold in the mini chocolate chips.
Divide the batter evenly among the mini muffin cups, filling each about ¾ full.
Bake for 12-15 minutes, or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the tin for a few minutes before transferring to a wire rack to cool completely.